Ethylene and propylene are important basic chemical feedstock. At present, ethylene and propylene are mainly produced through catalytic cracking or steam cracking of petroleum feeds. Catalytic cracking is performed at a reaction temperature of about 50 to 200° C. lower than that of steam cracking so that compared with conventional steam cracking, catalytic cracking has the following advantages: less energy consumption; reduced rate of coking on the inner well of the cracking furnace tube and thereby prolonged operating cycle and increased lifetime of furnace tube; reduced carbon dioxide emission; flexibly adjustable product composition; and increased total yield of ethylene and propylene.
U.S. Pat. No. 6,211,104 and Chinese Patent Application CN1504540A discloses a catalyst comprising 10 to 70 wt % of clay, 5 to 85 wt % of inorganic oxide, and 1 to 50 wt % of molecular sieve, which catalyst exhibits good activity for converting various conventional cracking feedstocks to light olefins, especially ethylene. The molecular sieve used is Y zeolite or ZSM molecular sieve having MFI structure with high Si/Al ratio, and the molecular sieve is impregnated with P/Al, Mg or Ca.
Chinese Patent Application CN1274342A discloses a molecular sieve catalyst having high Si/Al ratio and pore diameter of from 0.5 to 0.65 nm, and a process for producting ethylene and propylene by using said catalyst and light hydrocarbonaceous feed containing olefins.
Chinese Patent Application 00816642.0 discloses a process for the production of ethylene and propylene, wherein a hydrocarbonaceous feed containing naphtha is treated at 550-600° C. with a zeolite having pore diameters of less than 0.7 nm.
Chinese Patent Application CN1413244A discloses a process for catalytically cracking a hydrocarbon feedstock, which process comprises contacting the feedstock with a catalyst composition comprising a primary cracking component, such as zeolite Y, and a modified mesoporous aluminophosphate material.
However, there is still a need for a novel catalyst useful in the production of olefins via catalytic cracking, which catalyst has virtues of high catalytic activity, high yield of ethylene and propylene, and lower reaction temperature.